Glass laminates can be used as windows and glazing in architectural and vehicle or transportation applications, including automobiles, rolling stock, locomotive and airplanes. Glass laminates can also be used as glass panels in balustrades and stairs, and as decorative panels or covering for walls, columns, elevator cabs, appliances, electronic devices and other applications. Common types of glass laminates that are used in architectural and vehicle applications include clear and tinted laminated glass structures. As used herein, a glazing or a laminated glass structure (a glass laminate) is a transparent, semi-transparent, translucent or opaque part of a window, panel, appliance, electronic device, wall or other structure having at least one glass sheet laminated to a polymeric layer, film or sheet. However, glass laminates may also be used as a cover glass on signs, electronic displays, electronic devices and appliances, as well as a host of other applications.
Automotive glazing, laminated architectural glass and other glass laminates typically consist of two plies of 2 mm thick soda lime glass (heat treated or annealed) with a polyvinyl butyral (PVB) or other polymer interlayer. These glass laminates have certain advantages, including, low cost, and a sufficient impact resistance and stiffness for automotive and other applications. However, because of their limited impact resistance, these laminates usually have a poor behavior and a higher probability of breakage when getting struck by roadside stones, vandals and other impact events.
As the global fossil fuel reserves become depleted and prices get increasingly higher the world is looking for ways to reduce its consumption to conserve energy as well as to help mitigate possible global warming. For example, the automobile industries are looking for ways to increase mileage by reducing products' weights and improving engine efficiency. One way to reduce the weight is by using thinner glass windows while preserving or even improving the performance of the window glass or glazing. Corning Incorporated has taken the lead and developed various thin yet very strong glasses such as Corning Gorilla® glass to meet different future requirements. However, as glass sheets in laminates become thinner, the glass sheets become more pliable and more easily subject to deformation under stress, which often leads to optical distortion or shape variation when laminating such thin glass to form laminated glass products.
Typical glass lamination processes for the architectural and car window industries employ either vacuum bag or vacuum ring processes. In a typical vacuum bag process, the layers of the laminate are assembled in a stack, and the stack is wrapped in different films for lamination. There are release films to prevent stack/layers from sticking to the vacuum bag, breather films to facilitate vacuuming, and finally the vacuum bag to encase the sample in a vacuum environment for de-airing. On the other hand, in a typical vacuum ring process, a vacuum ring is used to seal the periphery of the stacked layers with a rubber ring seal, which has a built in vacuum line for vacuuming. Both processes impose stress on the materials being laminated and subsequently create optical distortion and shape variations, especially when laminating thin glass sheets having a thickness not exceeding 2.0 mm or not exceeding 1.0 mm.
There is a need for an apparatus and process for laminating thin glass laminate structures with improved optical distortion and shape consistency.
No admission is made that any reference cited herein constitutes prior art. Applicant expressly reserves the right to challenge the accuracy and pertinence of any cited documents.